Mechanical press with toggle lever crank drive

ABSTRACT

Drive mechanism for the slide of a mechanical press, especially a toggle lever crank press. In the slide driving mechanism means are provided comprising two eccentrics adjustable relative to one another for continuously changing the slide speed during its stroke, especially its slowing down close before the tool comes into contact with the stock to be worked.

United States Patent Kamelander Jan. 15, 1974 MECHANICAL PRESS WITH TOGGLE [56] References Cited LEVER CRANK DRIVE UNITED STATES PATENTS [75] Inventor; Ivan Kamelander, Brno, 2,280,587 4/1942 Klocke 74/38 Czechoslovakia 2,781,015 2/1957 Dehn et a]. 72/451 3,174,347 3/1965 Hecht 100/257 X [73] Assrgnee: Zdarske stro irny a slevarny, 3,426,635 2/1969 Nicklasson 74/38 X narodni podnik, Zdar nad Sazavou, Czechoslovakia Primary ExaminerHarvey C. Hornsby 22 d: 8 1971 Assistant ExaminerC. K. Moore 1 16 June Attorney--Arthur O. Klein [.21] Appl. No.: 150,982

[57] ABSTRACT 30 Foreign Application priority Data Drive mechanism for the slide of a mechanical press,

June [970 Czechoslovakia 704061 especially a toggle lever crank press. In the slide driving mechanism means are provided comprising two [521 U.S. c1 100/257 72/451 74/25 eccentrics adjustable relative amber [51] Int. Cl B30!) 5/00 tinuously changing the slide speed during its Stroke 58 Field of Search 160/257- 72/451- especially its 510mg befme comes into contact with the stock to be worked.

8 Claims, 6 Drawing Figures PATENTEDJMI 1 5 m4 SHEET 10F 3 INVENTOR VAN KAME LANDER 7642M (QIL U law I ATTORNEY memtnm 15 m4 SHEET 2 BF 3 @QQQ NOIISOd 30ns"H INVENTOR IVAN KAM LANDER ATTOR NEY MECHANICAL PRESS WITH TOGGLE LEVER CRANK DRIVE The present invention relates to crank driven toggle lever mechanical presses having reduced impact speed of the slide and thus of the tool on the workpiece.

The object of the invention is a press of the type in which a motor drives through gears, clutch and flywheel a rotating main shaft which imparts through a toggle lever connecting rod a reciprocating motion to the slide, the press having main drive means which imparts the motion to the top toggle lever substantially in the direction of the slide motion while auxiliary drive means is provided for simultaneously imparting a motion perpendicular to the direction of the slide motion. The combination of these two actions results in a reciprocating rectilinear motion of the slide having as its main feature a sharp slow-down on its down-stroke, whereby the speed of impact of the tool on the material is reduced; if required, such speed may be even reduced to zero.

The technological and economic advantages of this reduced impact speed are well-known, both from practice and in the literature.

There exists various mechanisms which realize the above-mentioned reduced impact speed of the tool on the material by the said combination of action on the toggle lever connecting rod, but they have a common drawback in that they do not have mechanical adjustable elements in the main drive means, nor do they have them in the auxiliary drive means. Such prior mechanisms are therefore designed for only a definite motion of the slide, i.e. they are suitable only for a certain operation, e.g. working upon material in a definite thickness range.

However, it is desirable in order to obtain good utilization of the machine, to provide the possibility of adjustment of other parameters of the slide motion:

a. impact and working speed b. length of working portion of stroke c. total stroke length d. lower dead point of slide.

The present invention eliminates the drawbacks of the prior art and is characterized in that the main drive means is adjustable for varying the motion of the top toggle lever of the connecting rod, and the toggle joint is controlled by a linkage system including adjustable elements from an auxiliary eccentric.

An example of embodiment of the present invention is shown in the accompanying drawings, in which:

FIG. 1 is a diagrammatic elevational view ofthe drive mechanism and the related elements of the machine;

FIG. 2 is a view in vertical section along the line II--II in FIG. 1;

FIG. 3 is a view similar to FIG. 2 but showing a multiple slide embodiment of the invention;

FIG. 4 illustrates examples of courses or cycles of slide strokes at reduced impact speeds;

FIG. illustrates diagrammatically the situation when the mechanism is adjusted according to the curve a in FIG. 4 and the slide position is at s, (minimum speed at the moment of impact); and

FIG. 6 illustrates diagrammatically the situation when the mechanism is adjusted according to the curve 0 in FIG. 4 (the slide being at top dead center).-

In the frame 1 of the press is fixedly mounted an axle 2 on which there is arranged for rotation a crank wheel 3 with a solid main eccentric 4 and a solid auxiliary eccentric 16. On the main eccentric 4 there is mounted an adjustable eccentric 5 having on its one face adjacent to the crank wheel 3 teeth 6 engaging with corre sponding teeth on an eccentric sleeve 7, the two sets of teeth being pressed into mesh by a nut 8 on a thread 9 formed on the hub of the crank wheel 3. The eccentric 4 may thus be adjusted angularly with respect to crank wheel 3 and thus with respect to eccentric 5 by loosening nut 8, turning parts 3 and 4 relative to each other, and then tightening nut 8.

On the adjustable eccentric 5 there hangs the upper toggle lever 10 of the connecting rod, lever 10 being connected by a joint pin 11 to the bottom toggle lever 12, which latter is attached by a pin 13 to a slide 14 which is movable within guides 15 on the frame 1.

An auxiliary eccentric is fixedly mounted on the hub of the crank wheel 3. On the auxiliary eccentric 16 there hangs an auxiliary pitman 17, pitman 17 being connected by a pin 18 to a slide block 19 movable within the slot of a first or upper arm of a two-arm or bell crank lever 20 by means of adjusting screw2l. The two-arm lever 20 is swingable on a pin 22 fixed in the machine frame 1, and its second or lower arm is connected by a pin 23 to a link 24, the: length of which can be varied by adjustment of a threaded rod 25. The link 24 is connected with the joint pin ll 1 of the toggle lever connecting rod. The radially highest zone of the auxiliary eccentric is preferably angularly displaced in relation to the radially highest zone of the main eccentric by 2040 in the direction opposite to the direction of rotation of the crank wheel 3.

The crank wheel 3 is driven in a way known per se from a motor (not shown) through. a flywheel, a clutch and brake, and possibly an intermediate shaft to a pinion 27 meshing with a ring gear on the crank wheel 3.

FIG. 3 shows an example of embodiment of a triplicate mechanism according to the present invention. The numerals 14a, 14b denote additional slides, the driving mechanism of each slide being the same as that above-described in the case of a simple slide.

The above-described mechanism functions as follows:

In the position shown in FIG. 1, the slide 14 is in its bottom dead position, the toggle lever connecting rod 10, 12 is straight, the eccentric 4 is at lower dead center, and the high point of the eccentric 16 is offset 20-40 with respect to eccentric 4 in the direction opposite the direction of rotation of the crank wheel.

When the crank wheel starts to rotate in the direction of the arrow in FIG. 1, the eccentrics 4, 5 lift the toggle lever 10 and the slide travels upwards. At the same time the eccentric 16 moves the pitman 17 to the right (FIG. 1) whereby through the two-arm lever 20 and the link 24 the pin 11 of the toggle lever is moved to the left in FIG. 1, out of the axis connecting the pins 2 and 13, thus forming an elbow" in the connecting rod and accelerating the upward movement of the slide. After rotation of the crank wheel 3, i.e. eccentrics 4, 5, by about the slide is in the top dead center position and starts to move downwards.

The linkage system 16-25 straightens the toggle levers 10, 12 of the connecting rod and the eccentrics 4, 5 arrive at approximately their top dead center position. The working portion of the slide motion now takes place in the following 90-1 10 of rotation of the crank wheel. At this time, the toggle levers 10, 12 of the connecting rod form an elbow and move the pin 11 to the right in FIG. 1 out of the axis passing through the pins 2, 13, so that a reduced speed of the downwardly moving slide is maintained for a certain time.

In the continuation of the downward movement of the slide, its speed increases again and has a course known for the standard crank mechanism, during which time the linkage system 16-25 returns the pin 11 back to the axis passing through the pins 2 and 13, i.e. straightens the elbow formed by toggle levers 10, 12 until they assume again the position in FIG. 1.

The various adjustments of the individual elements are:

By angularly adjusting the eccentric with respect to the crank wheel 3, the length of the working portion of the slide stroke is varied. The adjustment of the slide block 19 and thus the lengthening or shortening of the one, upper arm of the two-arm lever 20 provides for variation of the total length of slide stroke. The threaded rod adjusts the length of the link 24, and thereby adjusts the position of the pin 11 in relation to the slide motion as produced by eccentrics 4, 5, i.e. the value of the impact speed of the slide at the beginning of the stroke is adjusted.

By combining these adjustments, many variants of total slide stroke, length of working portion of stroke and speed of slide may be obtained to suit the operation in hand, i.e. one drive mechanism provides suitable conditions for operations requiring different parameters of the slide motion.

ln FIG. 4 there are shown examples of courses or cycles of slide strokes for various relative adjustments of the length of the working portion of the slide stroke and the length of total slide stroke. The curve denotes the course for maximum total stroke H, and maximum working portion of stroke p,. The curve C shows the maximum total slide H and nearly minimum working portion of the stroke s The curve d shows a nearly minimum total length of the stroke H and maximum working portion of the stroke 5 The curve e demonstrates minimum total length of the stroke H and nearly minimum working portion of the stroke s By shortening the link 24 it is possible to obtain a small reduction of both impact and working speed as shown by the curvefin FIG. 4 with the maximum total length of stroke H Although the invention is illustrated and described with reference to a plurality of preferred embodiments thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a plurality of embodiments, but is capable of numerous modifications within the scope of the appended claims.

What is claimed is:

1. A mechanical press having a reciprocable slide, a rotatable main shaft, means for driving the main shaft, a main drive means for reciprocating the slide toward and away from the main shaft, said main drive means comprising an eccentric mounted on the main shaft to be driven thereby, a toggle having links connected by a pivotal toggle joint drivingly connected between the eccentric and the slide auxiliary drive means imparting motion to the pivotal toggle joint between the toggle links in a direction substantially perpendicular to the motion of the slide, and means for adjusting said main drive means by varying the motion of the upper toggle link.

2. A press as claimed in claim 1, wherein said means for controlling the pivotal toggle joint comprises a linkage system including adjustable elements.

3. A press as claimed in claim 2, wherein said linkage system comprises a two-arm lever having a first arm adjustable in length, a cam driven by the main shaft, and a cam follower cooperating with the cam for driving said first arm.

4. A press as claimed in claim 3, wherein said first arm of the two-arm lever comprises a slide block and an adjusting screw.

5. A press as claimed in claim 3, wherein said linkage system comprises a link with length adjustment pivotally connected between the second arm of the two-arm lever and the pivotal toggle joint.

6. A press as claimed in claim 2, wherein said linkage system comprises a two-arm lever having a first arm adjustable in length by a slide block and an adjusting screw, and a link with length adjustment by a threaded rod, said link being pivotally connected between the second arm of the two-arm lever and the pivotal toggle joint.

7. A press as claimed in claim 6, wherein said linkage system is driven by a cam driven from the main shaft and a pitman extending between said last-recited cam and the first arm of the two-arm lever.

8. A press as claimed in claim 1, wherein the main drive means includes a combined eccentric comprising a second eccentric upon which said first-recited eccentric is mounted and with respect to which it is angularly 

1. A mechanical press having a reciprocable slide, a rotatable main shaft, means for driving the main shaft, a main drive means for reciprocating the slide toward and away from the main shaft, said main drive means comprising an eccentric mounted on the main shaft to be driven thereby, a toggle having links connected by a pivotal toggle joint drivingly connected between the eccentric and the slide auxiliary drive means imparting motion to the pivotal toggle joint between the toggle links in a direction substantially perpendicular to the motion of the slide, and means for adjusting said main drive means by varying the motion of the upper toggle link.
 2. A press as claimed in claim 1, wherein said means for controlling the pivotal toggle joint comprises a linkage system including adjustable elements.
 3. A press as claimed in claim 2, wherein said linkage system comprises a two-arm lever having a first arm adjustable in length, a cam driven by the main shaft, and a cam follower cooperating with the cam for driving said first arm.
 4. A press as claimed in claim 3, wherein said first arm of the two-arm lever comprises a slide block and an adjusting screw.
 5. A press as claimed in claim 3, wherein said linkage system comprises a link with length adjustment pivotally connected between the second arm of the two-arm lever and the pivotal toggle joint.
 6. A press as claimed in claim 2, wherein saId linkage system comprises a two-arm lever having a first arm adjustable in length by a slide block and an adjusting screw, and a link with length adjustment by a threaded rod, said link being pivotally connected between the second arm of the two-arm lever and the pivotal toggle joint.
 7. A press as claimed in claim 6, wherein said linkage system is driven by a cam driven from the main shaft and a pitman extending between said last-recited cam and the first arm of the two-arm lever.
 8. A press as claimed in claim 1, wherein the main drive means includes a combined eccentric comprising a second eccentric upon which said first-recited eccentric is mounted and with respect to which it is angularly adjustable. 